There is known a game device which obtains numerical value information based on a motion of a player and causes a subject to be operated to perform an action based on the numerical value information. For example, there is known a game device including a stick-shaped controller incorporating an acceleration sensor (for example, Patent Literature 1). With such a game device, it is possible to acquire a detection result of the acceleration sensor as the numerical value information, determine whether or not a player has swung the controller based on the numerical value information, and cause a game character to perform an action based on a judgment result thereof.
Therefore, examples of a game realized by such a game device as described above include a tennis game configured so that the game character swings a racket (bat, paddle) when the player swings the controller in the same manner as an actual racket. In this game, the game character swings the racket forehand when the player swings the controller forehand, while the game character swings the racket backhand when the player swings the controller backhand.